Why must lemon juice or citric acid be added to home canned tomatoes?
Tomatoes have a pH (acid) level that falls close to 4.6 – the line dividing high acid foods and low acid foods. It is important for the safety and quality of all home canned tomato recipes–sauce, whole & halved tomatoes, juice–that a proper acid level is maintained. Since many factors can decrease that natural acidity in tomatoes, the addition of bottled lemon juice or citric acid ensures the correct acidification in each jar. (Bottled lemon juice is recommended because its acid level is consistent, unlike fresh lemons that can have varied levels of acidity.) Recipes such as salsa, tomato chutney and pickles tomatoes generally include an adequate quantity of vinegar (5% acidity) and do not require additional acidification. Always follow a tested recipe. Do not alter the type of ingredients in the recipe or the quantities used.
